It seems that the flag "--verbose" and its shorter version "--v" are not supported by JTREG.

JTREG help for "verbose" word doesn't match the expectation.
From one side:
"""
$ jtreg --help verbose
Verbose Options
                These options control the amount of output written to the
                console while running tests

    -v | --v:<value> | -verbose | --verbose:<value>
. . .
"""

But an attempt to use "--verbose" results in error:
"""
$ java -jar /home/john22/workdir/java/jdks/tools/jtreg/7_4/jtreg/lib/jtreg.jar --verbose:all Hello
Error: Invalid option: --verbose
Usage:
         java -jar jtreg.jar options... tests...
. . .
"""

The "--verbose" option needs to be implemented. Otherwise remove it from "help".